Frequency representation in the rat cochlea

Hear Res. 1991 Feb;51(2):247-54. doi: 10.1016/0378-5955(91)90041-7.


In order to determine the place-frequency map of the rat cochlea, iontophoretic HRP-injections were made into the cochlear nucleus at electrophysiologically characterized positions. Distribution of retrograde HRP transport in cochlear spiral ganglion cells was analysed by means of a three dimensional reconstruction of the cochlea. The map was established for frequencies between 1.2 and 54 kHz, corresponding to positions between 96.5 to 2% of basilar membrane length (base = 0%). At apex of the cochlea the slope of the place-frequency map was below 0.25 mm/octave. The slope increased to a value of 2.1 mm/octave at 34% basilar membrane length, and remained almost constant towards the cochlear base. The close relationship between frequency range of highest sensitivity and maximum receptor- and innervation-density in the rat cochlea is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Cochlea / anatomy & histology
  • Cochlea / innervation
  • Cochlea / physiology*
  • Horseradish Peroxidase
  • Iontophoresis
  • Rats
  • Rats, Inbred Strains
  • Spiral Ganglion / anatomy & histology
  • Spiral Ganglion / physiology


  • Horseradish Peroxidase